Baffles, suppressors, and powder forming methods

ABSTRACT

A method of forming a firearm suppressor baffle including preparing a titanium alloy powder system, forming of the powder system into a green shape, optionally green machining the green shape, sintering the green shape to create a firearm suppressor baffle formed from sintered material, where the firearm suppressor baffle has an elevated oxygen content of between 0.2 and 0.5 weight percent. The resultant sintered material may have a creep value of less than 1.5% at 50 hours at 450 C. Also, a method of forming a firearm suppressor baffle including preparing a titanium aluminide powder system, forming the titanium aluminide powder system into a green shape through one of compaction and powder metal injection molding, and sintering the green shape to create the firearm suppressor baffle. The titanium aluminide powder method may also include deoxygenating the firearm suppressor baffle. Also disclosed are baffles and suppressors formed using these methods.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 15/372,018 filed Dec. 7, 2016, and entitled “BAFFELS,SUPPRESSORS, AND POWDER FORMING METHODS,” which claims the benefit ofU.S. Provisional Patent Application Ser. No. 62/264,225, filed Dec. 7,2015, and entitled “SUPPRESSOR AND POWDER FORMING METHODS FORMANUFACTURING,” the disclosures of which are hereby incorporated byreference herein.

BACKGROUND OF THE INVENTION

Suppressors or silencers (referred to herein as “suppressors”) are usedto reduce the amount of noise and/or muzzle flash emitted from a firearmupon firing. Typically, suppressors are constructed with an array orstack of cone shaped thin-walled baffles. This assembly creates acomplicated pathway designed to redirect and slow explosive gasesescaping from the barrel of the firearm while the projectile travelsthrough freely.

Because the suppressor baffles are stacked together they generallyrequire high precision with respect to their mating surfaces. Further,they need to be constructed of material that can withstand the heat andpressure that they are exposed to during use. Materials of constructionof conventional baffles are stainless steel, nickel base alloys, andtitanium.

Conventional forming routes for suppressor baffles include (i) machiningor (ii) casting followed by machining.

BRIEF SUMMARY OF THE INVENTION

Although well received, both methods have disadvantages from a materialscost perspective. Because the geometry of the baffle portion is athin-walled cone, a substantial amount of material must be removed toform the baffle shape via machining. In fact, when machining a baffle,the material removal can be over 90%. This adds time and cost to theforming process.

Casting a near-net article and then machining it is more efficient thanmachining alone, but still has an inefficient use of material when thematerial wasted in the central sprue and the feed sprues is considered.Further, casting often introduces voids into the material that can causeproblems in subsequent operations such as machining or welding. Powdermetallurgy manufacturing methods, including powder compaction and powdermetal injection molding (referred to collectively as “powder forming”),can provide improvements.

At a high level the powder forming approaches allow one to adjust analloy's chemistry by adding constituents during powder systempreparation to improve specific performance characteristics depending onthe application. In the case of baffles, high ductility (lowinterstitials, e.g. low oxygen) could be traded for increased strength,increased high temperature strength, or increased creep resistance byadding oxygen or silicon.

The present invention contemplates the manipulation of powderconstituents to improve high temperature behavior, whereas conventionaltesting of alloys has been focused on room temperature behavior. Indeed,strengthening an alloy at room temperature does not mean that the alloywill necessarily be stronger at high temperatures. This will bedependent upon the strengthening mechanism. For example, alloyssubjected to a conventional solution-treat-age cycle will have animproved microstructure (and improved mechanical performance) at roomtemperature, but heating the material will alter the microstructure anddiminish the high temperature properties. The present invention'sapproach is to instead alter the alloy chemistry at very low levels, toimprove high temperature performance. Once oxygen and/or silicon oranother material is added to the chemistry, the additive will remain,within reason, within the chemistry regardless of temperature. Theseelements strengthen the material by interstitial or substitutional meansrather than alpha/beta phase content or phase morphology basedmicrostructural mechanisms.

Further mechanisms such as oxide dispersion strengthening can continueto provide strengthening mechanisms at elevated temperatures.

In addition to the challenges of lowering cost and improving hightemperature strength an additional challenge is wear of the bore. Afterrepeated firing the hot gas and debris from the firearm propellant canerode the edges of the bore. The bore is typically very precise and theclearance between the bore and the projectile is critical to theperformance of the suppressor. Improving the wear resistance of a bafflematerial can extend the useful lifetime of the suppressor.

Aspects of Group 1:

In accordance with one embodiment of the present invention, there isprovided a method of forming a firearm suppressor baffle, the methodcomprising preparing a titanium alloy powder system, forming of thepowder system into a green shape, optionally green machining the greenshape, and sintering the green shape to create a firearm suppressorbaffle formed from sintered material; where the firearm suppressorbaffle has an elevated oxygen content of between 0.2 and 0.5 weightpercent.

In accordance with a further embodiment of the present invention, thereis provided a method of forming a firearm suppressor baffle, the methodcomprising preparing a titanium alloy powder system, forming of thepowder system into a green shape, optionally green machining the greenshape, and sintering the green shape to create a firearm suppressorbaffle formed from sintered material; where the firearm suppressorbaffle has an elevated oxygen content of between 0.2 and 0.5 weightpercent and approximately 0.3 weight percent.

In accordance with a further embodiment of the present invention, thereis provided a method of forming a firearm suppressor baffle, the methodcomprising preparing a titanium alloy powder system, forming of thepowder system into a green shape, optionally green machining the greenshape, and sintering the green shape to create a firearm suppressorbaffle formed from sintered material; where the firearm suppressorbaffle has an elevated oxygen content of between 0.2 and 0.5 weightpercent and the firearm suppressor baffle has an elevated siliconcontent of between 0.1 to 0.6 weight percent.

In accordance with a further embodiment of the present invention, thereis provided a method of forming a firearm suppressor baffle, the methodcomprising preparing a titanium alloy powder system, forming of thepowder system into a green shape, optionally green machining the greenshape, and sintering the green shape to create a firearm suppressorbaffle formed from sintered material; where the firearm suppressorbaffle has an elevated oxygen content of between 0.2 and 0.5 weightpercent and approximately 0.3 weight percent. The firearm suppressorbaffle also having an elevated silicon content of between 0.1 to 0.3weight percent.

In accordance with a further embodiment of the present invention, thereis provided a method of forming a firearm suppressor baffle, the methodcomprising preparing a titanium alloy powder system, forming of thepowder system into a green shape, optionally green machining the greenshape, and sintering the green shape to create a firearm suppressorbaffle formed from sintered material; where the firearm suppressorbaffle has an elevated oxygen content of between 0.2 and 0.5 weightpercent and the sintered material has a creep value of less than 8% at50 hours at 450 C.

In accordance with a further embodiment of the present invention, thereis provided a method of forming a firearm suppressor baffle, the methodcomprising preparing a titanium alloy powder system, forming of thepowder system into a green shape, optionally green machining the greenshape, and sintering the green shape to create a firearm suppressorbaffle formed from sintered material; where the firearm suppressorbaffle has an elevated oxygen content of between 0.2 and 0.5 weightpercent and the sintered material has a creep value of less than 1.5% at50 hours at 450 C.

In accordance with a further embodiment of the present invention, thereis provided a method of forming a firearm suppressor baffle, the methodcomprising preparing a titanium alloy powder system, forming of thepowder system into a green shape, optionally green machining the greenshape, and sintering the green shape to create a firearm suppressorbaffle formed from sintered material; where the firearm suppressorbaffle has an elevated oxygen content of between 0.2 and 0.5 weightpercent and the firearm suppressor baffle has an elevated siliconcontent of between 0.1 to 0.6 weight percent, the sintered materialhaving a creep value of less than 1.5% at 50 hours at 450 C.

In accordance with a further embodiment of the present invention, thereis provided a method of forming a firearm suppressor baffle, the methodcomprising preparing a titanium alloy powder system, forming of thepowder system into a green shape, optionally green machining the greenshape, and sintering the green shape to create a firearm suppressorbaffle formed from sintered material; where the firearm suppressorbaffle has an elevated oxygen content of between 0.2 and 0.5 weightpercent and preparing the powder system includes blending of metalpowder with at least one of titanium oxide, aluminum oxide powder, andsilicon.

In accordance with a further embodiment of the present invention, thereis provided a method of forming a firearm suppressor baffle, the methodcomprising preparing a titanium alloy powder system, forming of thepowder system into a green shape, optionally green machining the greenshape, and sintering the green shape to create a firearm suppressorbaffle formed from sintered material; where the firearm suppressorbaffle has an elevated oxygen content of between 0.2 and 0.5 weightpercent and forming is through one of compaction and injection molding.

In accordance with a further embodiment of the present invention, thereis provided a method of forming a firearm suppressor baffle, the methodcomprising preparing a titanium alloy powder system, forming of thepowder system into a green shape, optionally green machining the greenshape, and sintering the green shape to create a firearm suppressorbaffle formed from sintered material; where the firearm suppressorbaffle has an elevated oxygen content of between 0.2 and 0.5 weightpercent, the method further comprising hot isostatic pressing of thefirearm suppressor baffle.

In accordance with other embodiments of the present invention, a firearmsuppressor baffle is formed by any of the preceding methods of Group 1.

In still further embodiments of the present invention, any of thepreceding methods of Group 1 is used to form a plurality of firearmsuppressor baffles, where each firearm suppressor baffle is used in asuppressor.

Aspects of Group 2:

In accordance with additional embodiments of the present invention, amethod of forming a titanium alloy material comprises preparing atitanium alloy powder system, forming the titanium alloy powder systeminto a green shape through one of compaction and powder metal injectionmolding, sintering the green shape to create the titanium alloymaterial, the titanium alloy material having an oxygen content ofgreater than 0.2 weight percent and a creep value of less than 2% at 50hours at 450 C.

In accordance with additional embodiments of the present invention, amethod of forming a titanium alloy material comprises preparing atitanium alloy powder system, forming the titanium alloy powder systeminto a green shape through one of compaction and powder metal injectionmolding, sintering the green shape to create the titanium alloymaterial, the titanium alloy material having an oxygen content ofgreater than 0.2 weight percent and a creep value of less than 2% at 50hours at 450 C, further comprising hot isostatic pressing of thetitanium alloy material.

In accordance with other embodiments of the present invention, a firearmsuppressor baffle is formed by either of the preceding methods of Group2.

In still further embodiments of the present invention, either of thepreceding methods of Group 2 is used to form a plurality of firearmsuppressor baffles, where each firearm suppressor baffle is used in asuppressor.

Aspects of Group 3:

In accordance with a further embodiment of the present invention, amethod of forming a firearm suppressor baffle comprises preparing atitanium aluminide powder system, forming the titanium aluminide powdersystem into a green shape through one of compaction and powder metalinjection molding, sintering the green shape to create the firearmsuppressor baffle.

In accordance with a further embodiment of the present invention, amethod of forming a firearm suppressor baffle comprises preparing atitanium aluminide powder system, forming the titanium aluminide powdersystem into a green shape through one of compaction and powder metalinjection molding, sintering the green shape to create the firearmsuppressor baffle, and deoxygenating the firearm suppressor baffle.

In accordance with a further embodiment of the present invention, amethod of forming a firearm suppressor baffle comprises preparing atitanium aluminide powder system, forming the titanium aluminide powdersystem into a green shape through one of compaction and powder metalinjection molding, sintering the green shape to create the firearmsuppressor baffle, where oxygen content of the firearm suppressor baffleis below 600 weight ppm. This method may also include deoxygenating thefirearm suppressor baffle.

In accordance with a further embodiment of the present invention, amethod of forming a firearm suppressor baffle comprises preparing atitanium aluminide powder system, forming the titanium aluminide powdersystem into a green shape through one of compaction and powder metalinjection molding, sintering the green shape to create the firearmsuppressor baffle, where oxygen content of the firearm suppressor baffleis below 200 weight ppm. This method may also include deoxygenating thefirearm suppressor baffle.

In accordance with other embodiments of the present invention, a firearmsuppressor baffle is formed by any of the preceding methods of Group 3.

In still further embodiments of the present invention, any of thepreceding methods of Group 3 is used to form a plurality of firearmsuppressor baffles, where each firearm suppressor baffle is used in asuppressor.

Aspects of Group 4:

In accordance with an additional embodiment of the present invention, amethod of forming a titanium aluminide product comprises preparing atitanium aluminide powder system, forming the titanium aluminide powdersystem into a green shape, sintering the green shape to create asintered product, deoxygenating the sintered product to form thetitanium aluminide product.

In accordance with an additional embodiment of the present invention, amethod of forming a titanium aluminide product comprises preparing atitanium aluminide powder system, forming the titanium aluminide powdersystem into a green shape, sintering the green shape to create asintered product, deoxygenating the sintered product to form thetitanium aluminide product, where oxygen content of the titaniumaluminide product is below 600 weight ppm.

In accordance with an additional embodiment of the present invention, amethod of forming a titanium aluminide product comprises preparing atitanium aluminide powder system, forming the titanium aluminide powdersystem into a green shape, sintering the green shape to create asintered product, deoxygenating the sintered product to form thetitanium aluminide product, where oxygen content of the titaniumaluminide product is below 200 weight ppm.

In accordance with an additional embodiment of the present invention, amethod of forming a titanium aluminide product comprises preparing atitanium aluminide powder system, forming the titanium aluminide powdersystem into a green shape, sintering the green shape to create asintered product, deoxygenating the sintered product to form thetitanium aluminide product, where deoxygenating is by deoxidation insolid state (DOSS).

In accordance with an additional embodiment of the present invention, amethod of forming a titanium aluminide product comprises preparing atitanium aluminide powder system, forming the titanium aluminide powdersystem into a green shape, sintering the green shape to create asintered product, deoxygenating the sintered product to form thetitanium aluminide product, where deoxygenating is by molten saltelectrolytic methods.

In accordance with an additional embodiment of the present invention, amethod of forming a titanium aluminide product comprises preparing atitanium aluminide powder system, forming the titanium aluminide powdersystem into a green shape, sintering the green shape to create asintered product, deoxygenating the sintered product to form thetitanium aluminide product, where forming is through one of compactionand powder metal injection molding.

In accordance with an additional embodiment of the present invention, amethod of forming a titanium aluminide product comprises preparing atitanium aluminide powder system, forming the titanium aluminide powdersystem into a green shape, sintering the green shape to create asintered product, deoxygenating the sintered product to form thetitanium aluminide product, further comprising machining, includinggreen machine.

In accordance with other embodiments of the present invention, a firearmsuppressor baffle is formed by any of the preceding methods of Group 4.

In still further embodiments of the present invention, any of thepreceding methods of Group 4 is used to form a plurality of firearmsuppressor baffles, where each firearm suppressor baffle is used in asuppressor.

In accordance with a further embodiment of the present invention, thereis provided a method of forming a suppressor baffle, the methodincluding the step of powder forming the baffle with titanium powder,alloys thereof, or intermetallic powder. In the case of intermetallicpowder, the powder may be gamma titanium aluminide. The method of powderforming any of the noted materials may also include cold isostaticpressing followed by green machining, sintering, and final machining.Using this method, the resultant baffle may be manufactured toapproximately 98% dense. If slightly increased fatigue strength isrequired, the baffle may subsequently be hot isostatically pressed.Additionally, in the case of intermetallic powders such as titaniumaluminide, a post sintering deoxygenating process may be utilized.Baffles formed in this manner may be stacked within a suppressor.

A further embodiment of this invention is a suppressor constructed withbaffles formed from titanium aluminide, most preferably gamma titaniumaluminide. In other embodiments, the suppressor may be constructed fromtitanium powder, alloys thereof, or stainless steel.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter regarded as the invention is particularly pointed outand distinctly claimed in the concluding portion of the specification.The invention, however, both as to organization and method of operation,together with features, objects, and advantages thereof, will be orbecome apparent to one with skill in the art upon reference to thefollowing detailed description when read with the accompanying drawings.It is intended that any additional organizations, methods of operation,features, objects or advantages ascertained by one skilled in the art beincluded within this description, be within the scope of the presentinvention, and be protected by the accompanying claims.

With respect to the drawings, FIG. 1 shows a rear isometric view of abaffle in accordance with one embodiment of the present invention;

FIG. 2 shows an isometric cross-sectional view of the baffle of FIG. 1;

FIG. 3 shows an isometric cross-sectional view of a plurality of bafflesas shown in FIG. 1 stacked in tandem in an assembled relation;

FIG. 4 depicts a perspective view of a baffle assembly within asuppressor tube;

FIGS. 5A, 5B, and 5C depict non-limiting examples of alternate baffleconfigurations.

DETAILED DESCRIPTION

In the following are described the preferred embodiments of the BAFFLES,SUPPRESSORS, AND POWDER FORMING METHODS in accordance with the presentinvention. In describing the embodiments illustrated in the drawings,specific terminology will be used for the sake of clarity. However, theinvention is not intended to be limited to the specific terms soselected, and it is to be understood that each specific term includesall technical equivalents that operate in a similar manner to accomplisha similar purpose. Where like elements have been depicted in multipleembodiments, identical reference numerals have been used in the multipleembodiments for ease of understanding.

Rather than utilizing the conventional methods of (i) machining or (ii)casting followed by machining, it has been found that powder formingpresents efficient routes for manufacturing thin-walled cone geometriessuch as suppressor baffles. These net-shape or near net-shape formingroutes can substantially reduce the material wasted during the formingprocess without detriment to the finished product as compared to the twoconventional techniques. The materials can also be formed withheretofore unseen performance characteristics, particularly at elevatedtemperatures.

It will be appreciated that one of the existing challenges formanufacturing suppressor baffles is the lack of materials that are bothlightweight and capable of resisting the harsh environment created byrepeated weapon firing. Titanium alloys, titanium aluminides, andstainless steel offer both high temperature performance and oxidationresistance. Using powder forming approaches to form these articlesallows exacting control over the specific metallurgy and superiorcontrol over the microstructure.

For example, and particularly with titanium aluminides, use of a powderforming route eliminates the opportunity to form macro pores during thecasting process. Because titanium aluminides are especially brittle,macro pores are detrimental. Indeed, macro pores can be eliminatedcompletely using a powder forming route.

Further in the case of powder metallurgy, melting of the material iseliminated, permitting better control over the final microstructure byeliminating macro-segregation and providing for a more refinedmicrostructure. Depending on the specific geometry it may beadvantageous to use compaction forming methods, or for smaller or morecomplex geometries, powder metal injection molding methods.

Under the teachings herein, manufactured parts can be formed in anet-shape process or in a near net-shape process. Broadly, a net-shapeprocess can entail a metal injection molding operation and hard toolingto form the part in a net-shape fashion. Molded articles may then besintered to densify the article. If the required precision is outside ofthe process capability, the article may be machined after sintering.

A near net-shape process can entail a cold isostatic press and acombination of hard and soft tooling, or a die compaction process withhard tooling. The resulting preform may have some portions that are welldefined by the hard portion of the tooling and some portions that areless well defined. This green article can be further formed in the greenstate via machining. After green forming, the article can be sintered tohigh density, and possibly hot isostatically pressed when 100% densityis required, or at least greater than 98% density.

The powder materials used may include a pre-alloyed approach or ablended elemental approach. A powder metallurgy or powder formingapproach allows the economical forming of materials that are expensiveto cast, particularly titanium or intermetallics, such as gamma titaniumaluminide.

Performance additives may also be provided with the powder preparationstep. Oxygen can be added by blending in titanium oxide or aluminumoxide powder (in the case of Ti-6Al-4V). Silicon can be added byblending in fine silicon powder. Alternatively, the additionalconstituents can be specified to be present in the titanium powder.

Titanium powder is available in a wide range of oxygen contents.Commercially available titanium powder can range from 0.08 weightpercent oxygen to over 0.7 weight percent oxygen, oxygen content isdependent upon the particle size distribution, the process used tomanufacture the powder and the care used by the manufacturer of thepowder. However, commercially available powders over 0.2 weight percentare not used for high performance applications and are reserved forcosmetic, pyrotechnic, or gettering. Custom alloys with other materialsin them (such as increased silicon) could also be made or specified. Ithas been found, however, that the most practical technique is to blendin those performance additives at the powder preparation stage. In oneexample, titanium powder with 0.3 weight percent oxygen is utilized.

The preferred method of producing finished thin-walled parts such assuppressor baffles is the near net-shape process using cold isostaticpressing followed by green machining, sintering, and final machining.Using this route, baffles can be manufactured to about 98% dense, and inmost case this will provide adequate strength for the finished product.If increased fatigue strength is required, the baffles may subsequentlybe hot isostatically pressed.

After pressing the green part can be green machined prior to sintering.This allows the removal of any excess material as well as the additionof details that are challenging or impossible to form during pressing.

At a high level the powder metal forming process, including aspects ofboth conventional powder metallurgy and powder metal injection molding,has steps that can include the following:

Powder system preparation: The powder may be blended with alloyingcomponents, sintering aids, pressing lubricants or binders, etc. In thisstage performance enhancing additives may also be provided; for example,oxygen or silicon.

Compaction/forming: The powder system is formed into a green shape. Thisforming may be performed by a compaction method such as die compactionor cold isostatic pressing, or a binder assisted forming process such aspowder metal injection molding.

Green machine: A green machining process may be used to add additionalfeature to the green article or to remove excess material.

Sintering: Green articles are thermally processed to sinter the powderand create a sintered product.

Deoxidizing: In the case of titanium aluminides, the sintered productmay be deoxidized in a deoxidizing process, such as deoxidation in solidstate (DOSS), molten salt electrolytic methods, or other deoxidation orreduction processes. Deoxidation may be performed before or aftermachining.

Final machining and finishing: Sintered parts (including deoxidizedsintered parts) can be machined to add features or create more precisedimensions. Secondary operations such as hot isostatic pressing,polishing, or deburring may also be performed.

In the case of baffles, the powder forming route offered can reducemanufacturing costs while increasing performance. Baffles are subjectedto high temperatures and pressure due to the expansion of hot gas out ofthe firearm and into the suppressor. It is at these high temperature andpressures where performance is demanded. The two performance standardstested were high temperature tensile strength and high temperaturecreep.

Titanium Alloy Considerations

The creep resistance of titanium baffles can be improved by using powderforming methods to create a baffle with enhanced high temperature creepperformance beyond that of those formed from conventional means. Inpreferred embodiments, high temperature creep performance is enhanced byelevating oxygen levels to between 0.2 and 0.5 weight percent andoptionally silicon to between 0.02 and 0.6 weight percent. In otherembodiments, silicon levels may be elevated without oxygen beingelevated.

Table 1 compares the elevated temperature tensile strength and creepresistance for several materials at 450 C. All samples were tested usingASTM E139-11: Standard Test Methods for Conducting Creep, Creep-Rupture,and Stress-Rupture Tests of Metallic Materials and ASTM E21-09: StandardTest Methods for Elevated Temperature Tension Tests of MetallicMaterials. Sample 1 was prepared from commercially available titaniumround stock and Samples 2-4 were prepared via powder forming methods,which allowed the alloy components to be manipulated.

By elevating the oxygen level of the TI-6Al-4V alloy to 0.3 weightpercent (from 0.13 weight percent), a substantial increase in creepstrength is observed over the conventional material of Sample 1. WhileSample 1 showed substantially higher tensile strength values for bothultimate and yield tensile strengths, it had a substantially lower creepresistance. This is initially counter-intuitive, yet it serves todemonstrate that tensile strength performance does not necessarilyindicate improved creep resistance. For certain manufactured parts, suchas firearm suppressor baffles, creep resistance quality can outweighyield strength.

Sample 1 has a wrought microstructure resulting in higher initialstrengths, however the microstructural advantages are not stable overtime at elevated temperature. By increasing the oxygen content to 0.3weight percent, the creep performance of the Ti-6Al-4V titanium isincrease by more than an order of magnitude. Further improvements increep and tensile strength are seen with additions of silicon to thealloy in Samples 3 and 4. It is worth noting that the improvement ofSamples 3 and 4 over Sample 2 do not come at any appreciable cost to theelongation values.

TABLE 1 Tensile strength and creep performance of Ti—6Al—4V materials at450 C. Ultimate Yield Tensile Tensile Creep (%) Oxygen Silicon StrengthStrength Elongation (450 C./58 ksi) Sample Condition (wt %) (wt %) (ksi)(ksi) (%) (50 h) 1 Wrought 0.13 — 97.8 82.6 24.0 9.33 2 Beta- 0.30 —80.8 63.5 15.5 0.88 annealed 3 Beta- 0.30 0.09 83.9 71.1 15.5 0.52annealed 4 Beta- 0.30 0.3 89.4 73.6 17.0 0.27 annealed

While the relationship of oxygen content to tensile strength at roomtemperature is well understood, tensile strength at room temperatures isnot necessarily indicative of high temperature strength or creepresistance. Other observations serve to demonstrate how this is notintuitively scalable. Table 2 compares the performance of two powdermetal processed alloys, both of which have an oxygen level of 0.3 weightpercent. Both materials were formed from powders and beta annealed anddemonstrate how different strengthening mechanisms have outsized effectsat elevated temperatures. While Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Momaterial have similar tensile strengths at elevated temperature, theseproperties depart substantially with respect to creep. There is about a1.1× increase in high temperature tensile strength between the twoalloys, but almost a 15× increase in creep resistance.

TABLE 2 Comparison of elevated temperature performance of PM Ti Alloymaterials Ultimate Tensile Strength Creep (%) Oxygen (ksi) (450 C./58ksi) Powder Metal Alloy (wt %) (450 C.) (50 hr) Ti—6Al—4V 0.3 80.8 0.88Ti—6Al—2Sn—4Zr—2Mo 0.3 89.1 0.06

To improve wear properties of the finished article hard particles can beincluded in the alloy. Titanium carbide can be added at levels between0.5 and 35 weight percent to improve both wear and creep resistance.

Previously developed alloys having improved temperature resistance canalso be employed or modified. Ti-6Al-2Sn-4Zr-2Mo-0.08Si is a knownalloy. In an embodiment, a baffle is made ofTi-6Al-2Sn-4Zr-2Mo-0.3O-0.08Si by powder methods. In another embodiment,this alloy is formulated as a metal matrix composite, with 15 weightpercent titanium carbide.

Similar improvements can be made to other high performance materialssuch as nickel base super-alloys.

Stainless Steel Considerations

Stainless steel can also be used to fabricate parts such as suppressorbaffles. In this respect 17-4ph is a preferred material because of itshigh tensile strength. The powder forming route allows for theincorporation of strengthening mechanisms to stainless alloys. Thedesired alloy can be fabricated by atomization, mechanical alloying, apowder blending approach or other method of creating a dispersed oxidesystem. There are many other additions that can be used to improve creepand temperature resistance, among them carbon or molybdenum.

There are several challenges to manufacturing stainless steel bafflesvia powder forming. The application is price sensitive and consequentlyraw material cost is a consideration. Coarse powder is less expensivethan fine powder so it is a preferable raw material. A challenge ofprocessing coarse stainless steel via powder forming methods is that thecoarse particles do not sinter as easily as fine powders. To achievecomparative tensile strength competitive with conventional stainlesssteel, powder formed stainless steel requires high sintered densities,preferably 98% dense or greater.

Corrosion resistance is also an issue when sintering stainless steel. Toachieve appropriate corrosion resistance the powder should be sinteredwell above closed porosity, preferably 98% or greater.

Another challenge is that stainless steel does not have the favorablehigh temperature performance of nickel based super-alloys and does notoffer substantial weigh reduction when compared to nickel based alloys.It is desirable to improve the high temperature performance of stainlessbaffles.

It has been found that by optimizing the stainless alloy chemistry viapowder metallurgy, one may provide for adequate tensile strength andcorrosion resistance while increasing the high temperature performance.It has also been found possible to use coarse stainless powder (powderhaving a d90 of 75 microns or greater) to form baffles sintered to nearfull or full density.

By adding silicon to the stainless chemistry, sintering can be aided byforming a liquid phase and high temperature performance can be improved.Typically, sintering improvement can be made between 1 and 6 weightpercent silicon. Typically, high temperature properties can be improvedby adding 0.2 to 3.0 weight percent.

The addition of silicon to a 17-4 stainless steel powder system cansignificantly improve its sintering. Pre-alloyed 17-4ph stainless steelpowder having a d90 of 75 microns that is isostatically pressed and thensintered could not achieve a density of about 95.5 percent. However, theaddition of 3% silicon allowed the material to sinter to over 99.5percent dense.

There are multiple alloying routes that can be used to improve the hightemperature performance of stainless steels. Further or additionalbenefits can be made by the addition of molybdenum carbon or otherelements depending on the specific alloy chemistry. Carbon contents varybetween 0.1 and 1.0 weight percent. It is also possible to increase thechromium content and potentially the nickel content; or incorporatenitrogen, silicon, or rare earth metals into the alloy.

Stainless powders can be die compacted or cold isostatically pressed.Lubricant can be added to improve the compaction behavior and binderscan also be added to further improve the green strength and greenmachinability of the compact. Binder content can range in between 0 and5 weight percent.

Titanium Aluminide Considerations

With respect to titanium aluminide, additional challenges exist toprocessing this material via a powder route. These challenges are basedin the material's sensitivity to contamination such as carbon or oxygenand the limited availability of low contamination powder. While thereare analogs of this problem present in titanium powder processing, it isseverely aggravated in the realm of titanium aluminide. Specificationsmay limit oxygen content to below 600 weight ppm, which is verychallenging to obtain in a commercial powder product let alone maintainin a sintered compact made from fine titanium aluminide powder.

By incorporating a deoxidizing process after sintering, these challengescan be overcome. Deoxygenation processes for titanium are typically notpractical because they add cost, and more importantly it is difficult tocontrol what the final oxygen content will be. In typical titaniumalloy, there is an oxygen range over which optimal properties areachieved, below the lower limit of this range the titanium materialswill exhibit decreased tensile strength and above the upper limit ofthis range the material will become embrittled. Because of theirdifferences in atomic structure when compared to metal alloys, titaniumaluminide and other intermetallics are more sensitive to highinterstitial contamination, but not dependent on it to improve theirproperties at low level. Thus, the ability to control the exact level ofoxygen remaining after deoxygenation is not as critical to finalproperties provided a level below a certain maximum oxygen level isobtained. Consequently, deoxygenation processes that would be consideredimpractical for titanium alloys can be employed with titanium aluminidesto produce higher performance materials more effectively. Theseprocesses include deoxidation in solid state (DOSS), molten saltelectrolytic methods, or other known deoxidation or reduction processes.Moreover, it has been found that oxygen levels can be driven below 200parts per million without considerable detrimental effects.

Baffle configurations formed by these powder forming processes maydiffer considerably. Nevertheless, FIG. 1 shows a rear isometric view ofa baffle 100 in accordance with one embodiment of the present invention.FIG. 2 shows an isometric cross-sectional view of the baffle of FIG. 1.Viewed together, it will be appreciated that the baffle 100 is generallycylindrical with a conical taper. Indeed, the baffle 100 includes amajor cylindrical section 102 with a minor cylindrical section 104extending therefrom to create a first shoulder 106. A second shoulder108 is formed where the minor cylindrical section 104 meets the largestdiameter of a conical section 110. The overall length L of baffle 100 is60 mm but can be altered per design considerations.

It will be further appreciated that the baffle 100 is hollow, forming abore 112 through its centerline 114. Bore 112, and particularly theinterior surface 116 thereof, follows the geometry of the majorcylindrical section 102, first shoulder 106, minor cylindrical section104, second shoulder 108, and finally the conical section 110. Being“thin-walled,” the baffle has a thickness “T” which is orders ofmagnitude thinner than length L, for example 1.5 mm. This thickness isbest observed at first end 118 or second end 120.

FIG. 3 shows an isometric cross-sectional view of a baffle assembly 300,consisting of a plurality of baffles as shown in FIG. 1 stacked intandem. To configure such an assembly 300, baffles, for example baffles100 and 200, are oriented in the same “direction”, here with theirconical sections 110, 210 facing toward the viewer's left. The baffles100, 200 are then brought into contact with each other such that thefirst end 118 of baffle 100 abuts the exterior of first shoulder 206 ofbaffle 200. Portions of the bore 112 of baffle 100, particularly asection of major cylindrical section 102, frictionally engages theexterior of minor cylindrical section 204 of baffle 200. Additionalbaffles can then be added to the assembly 300 as shown in FIG. 3.

In the orientation of assembly 300 shown in FIG. 3, it will beappreciated that a projectile (not shown) fired from a firearm (notshown) will travel from the viewer's left to right, straight throughbores 112, 212. Gasses expelled from the firearm with the projectilewill expand into cavities 302, 304, 306, 308, etc. upon firing. It isthese cavities 302, 304, 306, 308, etc. which aid in dissipating energyfrom the blast to suppress sound and flash from the firearm.

The assembly 300 of FIG. 3 may itself form a suppressor, for examplewhere the baffles 100, 200, 300 are welded together. Alternatively,baffle assemblies may be fitted within a suppressor tube 400 as shown inFIG. 4. Suppressor tubes, such as suppressor tube 400, are typicallycylindrical and include threaded connections 402 for threading onto thebarrel of a firearm as well as an end cap (not shown) for retaining thebaffles in the assembly.

Other baffle types, all of which may be produced using the techniquestaught herein, are shown in FIGS. 5A, 5B, and 5C. These include the Kbaffle 502, conical baffle 504, and step cone baffle 506. Additionalbaffle configurations may also be provided.

Although not shown, the baffles may include additional features to aidin dissipation of this energy. For example, apertures may be formed inbaffle, for example in the conical section or the second shoulder.Various holes ports and vents and other elements can be added to direct,divert and manipulate the gas flow.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

1.-20. (canceled)
 21. An article of manufacture comprising: a titaniumalloy component, said titanium alloy component having a creep value ofless than 1.5% at 50 hours at 450 C and an elevated oxygen content ofbetween 0.2 and 0.5 weight percent.
 22. The article of manufacture ofclaim 21, wherein the elevated oxygen content of said titanium alloycomponent is approximately 0.3 weight percent.
 23. The article ofmanufacture of claim 21, wherein said titanium alloy component has anelevated silicon content of between 0.1 to 0.6 weight percent.
 24. Thearticle of manufacture of claim 21, wherein of said titanium alloycomponent has an elevated silicon content of between 0.1 to 0.3 weightpercent.
 25. The article of manufacture of claim 21, wherein saidtitanium alloy component comprises a Ti-6Al-2Sn-4Zr-2Mo alloy.
 26. Thearticle of manufacture of claim 21, wherein of said titanium alloycomponent comprises a Ti-6Al-4V alloy.
 27. A firearm suppressorcomprising: at least one titanium alloy baffle, wherein said at leastone titanium alloy baffle has a creep value of less than 1.5% at 50hours at 450 C and an elevated oxygen content of between 0.2 and 0.5weight percent.
 28. The firearm suppressor of claim 27, wherein theelevated oxygen content of said at least one baffle is approximately 0.3weight percent.
 29. The firearm suppressor of claim 27, wherein said atleast one baffle has an elevated silicon content of between 0.1 to 0.6weight percent.
 30. The firearm suppressor of claim 27, wherein said atleast one baffle has an elevated silicon content of between 0.1 to 0.3weight percent.
 31. The firearm suppressor of claim 27, wherein said atleast one baffle is a plurality of baffles.
 32. The firearm suppressorof claim 27, wherein said at least one baffle comprises aTi-6Al-2Sn-4Zr-2Mo alloy.
 33. The firearm suppressor of claim 27,wherein said at least one baffle comprises a Ti-6Al-4V alloy.
 34. Thefirearm suppressor of claim 27, wherein said at least one titanium alloybaffle is a plurality of titanium alloy baffles, and wherein less thanall of said plurality of titanium alloy baffles have a creep value ofless than 1.5% at 50 hours at 450 C and an elevated oxygen content ofbetween 0.2 and 0.5 weight percent.
 35. A firearm suppressor bafflecomprising: a titanium alloy, wherein said titanium alloy has a creepvalue of less than 1.5% at 50 hours at 450 C and an elevated oxygencontent of between 0.2 and 0.5 weight percent.
 36. The firearmsuppressor baffle of claim 35, wherein the elevated oxygen content ofsaid titanium alloy is approximately 0.3 weight percent.
 37. The firearmsuppressor baffle of claim 35, wherein said titanium alloy has anelevated silicon content of between 0.1 to 0.6 weight percent.
 38. Thefirearm suppressor baffle of claim 35, wherein said titanium alloy hasan elevated silicon content of between 0.1 to 0.3 weight percent. 39.The firearm suppressor of claim 35, wherein said titanium alloy is aTI-6Al-2Sn-4Zr-2Mo alloy.
 40. The firearm suppressor of claim 35,wherein said titanium alloy is a Ti-6Al-4V alloy.